This was on ok biography of Mark Twain. I've read better. The pictures were fabulous though. It would be an ok book for elementary kids, but definitely subsidize it with something that cites sources for any kind of research or teaching.
I just recently discovered the Great Names series was actually originally written in either Mandarin or Cantonese and then translated into English. That might explain why every once in a while there are typos, and why there is no bibliography citing any sources for the information in the book.